1. Field of the Invention
The present invention relates to a fixing member for use in a heat fixing apparatus of an electrophotographic image forming apparatus, a method for manufacturing the same, a fixing apparatus, and an image forming apparatus.
2. Related Background Art
A fixing member for use in a heat fixing apparatus of an electrophotographic image forming apparatus such as a printer, a copier, and a facsimile includes a film-shaped member and a roller-shaped member. As such a fixing member, a fixing member is known in which an elastic layer made of a heat resistant rubber or the like is, if necessary, formed on a film- or a roller-shaped base member made of a heat resistant resin or a metal, and a surface layer contains a fluororesin having excellent release properties to a toner. Herein, a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) excellent in heat resistance can be used as the fluororesin contained in the surface layer.
By the way, in association with an increase in printing speed in recent years, the fixing member tends to be demanded to have more increased durability. Therefore, in order to increase the durability of the fixing member, many studies for enhancing the wear resistance of the fluororesin layer have been made.
Then, Japanese Patent Application Laid-Open No. 2010-181621, which describes the invention relating to a non-rotating pressure member to be arranged on a fixing unit of an image forming apparatus of an electrophotographic system, discloses that wear resistance of a crosslinked fluororesin layer formed through the following steps 1 to 4 is remarkably enhanced:
step 1: forming an unfired and uncrosslinked fluororesin layer on a base member,
step 2: heating the fluororesin layer to a temperature ranging from the melting point (Tm) of the fluororesin to a temperature higher than the melting point by 150° C. (Tm+150° C.), and firing the resultant,
step 3: adjusting the temperature of the fired uncrosslinked fluororesin layer within the range from a temperature lower than the melting point of the fluororesin by 50° C. (Tm−50° C.) to a temperature higher than the melting point by 50° C. (Tm+50° C.), andstep 4: irradiating the uncrosslinked fluororesin layer, the temperature of the layer being adjusted, with radiation having an irradiation dose ranging from 1 to 1000 kGy under an atmosphere having an oxygen concentration of 0.1 to 1000 ppm to crosslink the uncrosslinked fluororesin.
Then, in Japanese Patent Application Laid-Open No. 2010-181621, specific examples of the fluororesin include polytetrafluoroethylene (PTFE), a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and a tetrafluoroethylene-hexafluoropropylene copolymer (FEP).